Math question: In triangle ABC, angle A is bisected by the line segment AD. If angle B is 60 degrees and angle C is 80 degrees, find the measure of angle A.
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What is the value of f(x) when c = -5 in the constant function f(x) = c?
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What is the radius of a circle with a function f(x) = x^2 + y^2, if the function outputs a constant value of r^2?